A new Berkeley study shows that fracking-induced earthquakes can generate significant anxiety in the public.
Since 2010, when fracking for natural gas and oil in Oklahoma began in earnest, there has been a concomitant increase in seismicity, with many earthquakes induced by wastewater injection from fracking and other drilling operations.
The new study was published in the journal Environmental Epidemiology by Dr. Joan Casey and fellow researchers in the School of Public Health at UC Berkeley. It is known that large single earthquakes cause mental health repercussions, but the health implications of these new not-so-large-but-frequent earthquakes have not been studied before.
Casey and colleagues used a novel technique to examine the associations between the Oklahoma earthquakes and statewide anxiety - a time-series analysis to find increased anxiety-related Google search episodes following Oklahoma earthquakes of ≥ magnitude 4 between January 2010 and May 2017. Earthquakes of less than magnitude 4 generally cannot be felt over a large area, just near the epicenter.
The U.S. Geologic Survey’s Advanced National Seismic System Comprehensive Catalog supplied earthquake dates and magnitudes (Figure 2). The research team used the Google Health application programming interface to compile the proportion of weekly Oklahoma-based health-related search episodes for anxiety. A quasi-experimental time-series analysis from January 2010 to May 2017 evaluated monthly counts of earthquakes ≥ magnitude 4 in relation to anxiety, controlling for US-wide anxiety search episodes and Oklahoma-specific health-related queries.
Between January 2010 and May 2017, the USGS measured 8,908 earthquakes across the state of Oklahoma, with an average of 218 earthquakes per month. The average number of ≥ M 4 earthquakes each year increased from 3 to 22 during the periods 2010–2013 and 2014–2016, respectively (Figure 3A).
Interest in earthquakes as measured by the proportion of Google searches for ‘earthquake’ tracked with actual events in Oklahoma during the study period.
The observed proportion of Google search episodes originating in Oklahoma and focused on anxiety increased over the test period (Figure 3B). These Google searches in Oklahoma were positively associated with similar search episodes nationwide.
During the 7-year study period, Oklahoma experienced an average of two earthquakes per month of greater than magnitude 4. For each additional earthquake ≥ magnitude 4, the proportion of Google search episodes for anxiety increased by 1.3% and 60% of this increase persisted for the following month. In months with 2 or more ≥ magnitude 4 earthquakes, the proportion of Google search episodes focused on anxiety increased by 5.8%. In a sub-analysis, Google search episodes for anxiety peaked about 3 weeks after ≥ magnitude 4 quakes.
The cause of the anxiety following earthquakes might seem obvious, but other research implies that coping with the damage caused by earthquakes could induce psychological distress. Survey respondents living in an area with induced earthquakes in the Netherlands named property damage and reduced value of homes as their primary concern and a cause of anger and worry.
The value of homes in Oklahoma—where builders have not constructed earthquake-resistant structures—appears to drop after moderate earthquakes. Governor Mary Fallin has also twice declared a state of emergency after earthquakes in 2016. These events may result in concerns about safety and economic loss perhaps causing, in turn, some of the anxiety gauged by Google searches.
Although there is a chance that using internet queries can bias results by underrepresenting those who do not use the internet, most households in Oklahoma (71.1%) had high-speed internet access during this time period. In addition, the majority of Americans now seek health information online and most use the internet as their first source of health information.
The research group weeded out many other statistical control issues like specifying within-Oklahoma monthly Google queries for ‘toothache’ as a covariate to reduce errors arising from coincidences between earthquakes and nonspecific or hypochondriacal pain among Oklahomans. Previous research suggests that much of reported tooth pain may come from psychosomatic origins and that populations living in noisome, but not otherwise toxic, environments report toothache more than other populations, controlling for socioeconomic and demographic characteristics.
The connection between fracking and earthquakes in the central and eastern United States is clear (see Figure 4 below). But the earthquakes are not a result of fracking itself. Fracking takes a few hours to a few days, followed by a period where the fracking fluid is allowed to flow back to the surface where it is collected for disposal, treatment, or reuse.
It is the disposal of this fluid, along with other waste and produced waters even from non-fracking wells, by injection into deep wells at depths well-below the fracking horizon that causes earthquakes.
But the trade-offs may be worth the anxiety. Dramatic increases in hydraulic fracturing, directional drilling and other technologies have allowed natural gas production in the U.S. to increase by over 40%, and crude oil production by over 80%, between 2006 and the present (see Figure 1 above). This has essentially made the United States energy independent and won the US-OPEC oil war that had been raging since 2014.
The fracking craze is also responsible for the dramatic drop in carbon emissions in America because it has provided enough gas at cheap prices for natural gas to replace coal. Our emissions are now at a 27-year low. There is strong evidence that this trend will continue for decades and that natural gas will be the major source of energy in the United States by 2050.
Most fracking and wastewater injection operations do not induce earthquakes. Either they don’t have high enough injection rates and total water volumes to change the subsurface pressures, or they are not close enough, or connected by subsurface fluid pathways, to sufficiently large faults. These observations form the basis for changing injection protocols so that we avoid inducing earthquakes above M4 altogether.
An important difference between this study and those concerning the psychological effects of larger infrequent earthquakes, is that smaller, more frequent earthquakes can have an effect that lasts longer, although the effects are less severe.
Such studies should be expanded, because we need to better understand how technology and society interacts as our society becomes even more technological. And as we get even more gas and oil out of the ground in the coming decades.
